The present invention relates to a cover, particularly a mulch cover for covering cultures so as to improve soil conditions and to enhance plant growth under utilization of biologically active as well as synthetic material.
New plants in horticultures including tree arboretums and other forrestry facilities, also including gardening parks etc. i.e. in all situations where an attempt is made to grow new plants. These plants are always subjected to a significant extent to various, even violent natural conditions, such as severe weather, unfavorable climate and so forth. Growth therefore will be detrimentally influenced through weeds, lack of moisture (or too much moisture), excessive or insufficient solar radiation etc.
Fighting weeds has been carried out in a chemical fashion which however from any point of view, "loads" the ecology and is frowned upon to an increasing extent. Therefore, it has been suggested to provide covers, for example for covering small plants but it was found that these covers for some reason extract nutrients from the soil. Thus in order to offset this detrimental side effect one has used twigs, straw, peat, bark, wood shavings or the like. All this has been carried out on an experimental basis in order to reduce the growth of competing weeds. Also, the germination conditions and local climate is to be improved while soil compaction is to be prevented i.e. the soil should always remain more or less loose and crumbly. In addition, new desired growth may require shading and finally air circulation and moisture conditions often require improvements of the local conditions in one form or another while particularly excessive dryness is to be avoided (at least in most instances). It is important to realize that the conditions are variable and difficult to generalization.
Any cover needed in that fashion is of course not a general one and requires variations which depend on the kind of growth that is to be enhanced on one hand and the kind of growth that is to impeded on the other hand. In case of forrestry e.g. one expects the cover to remain useful through three of four vegetation periods. In gardening however one, or two at the most, may prove to be sufficient. Following the vegetation period it is expected that the material of which a cover is made has more or less rotted away and does not require any kind of removal. The mulch methods have established that straw is particularly good; it takes about 3 to 4 years before it is rotted without any residue that loads the environment. On the other hand it is a disadvantage that straw has to be more or less uniformly distributed e.g. the amount of 4 kg/m.sup.2 but that is often difficult to obtain. On the other hand rotting of straw was found later on to particularly enhance the growth of weeds.
In order to offset the aforementioned problems foil mulching was introduced i.e. the soil was covered with a black foil which was light impermeable and thus prevents the germination of any weeds. This approach has the highly undesirable side effect in that the foil itself will not deteriorate and will have to be removed later. Moreover the supply of the desired plants which grow in between adjacent foils, with nutrients and fertilizer is no longer certain and may in fact become quite irregular. Also, rain water may in fact be completely deflected and run off from the growth area. Neither the feeding and supply of moisture is adequate.
In order to offset the aforementioned drawbacks without foregoing the respective advantages it was suggested to provide mulch covers in the form of mats or the like made of natural material. These mats were made of compacted or compressed straw. They lasted from 3-5 periods of vegetation and growth and still were rotting adequately but still there was certain amount of light permeability and the rotting as stated earlier still promoted the growth of weeds. Particular evil weeds such as thistles, certain grasses and others could not be avoided and wherever just little light passes through the mat the weeds will grow.